Method and apparatus for dispensing gas material



Oct. 28,v 1941. G. H. zr-:NNER' METHOD AND APPARATUS FOR DISPENSING GAS MATERIAL Filed Aug. '7, 1937 3 SheebS-Sheet l Wod NN fw/m23 V515,

lNvx-:NTOR GEORGE. HZENNER ATTORNEY Oct. 28, 1941. 2,260,357

METHOD AND ABPARATUS FORDISPENSING GAS; MATERTM.l

G. H. 'ZENNER 5 sheets-smet 2 Filed Aug. '7, 1937 III A 3/ lNVENTOR l l GEORGE' H.ZENNER 87 eff/g5 ATTORN EY Oct. 28', 1941. v G. H. zENNER 2,250,357

METHOD AND APPARATUS FOR DISPENSING GAS MATERIAL Filed Aug. 7. 1957 5 sheets-sheet 3 ATTORN EY Patented Oct. 28, 1941 METHOD AND APPARATUS FOR DISPENSING GAS MATERIAL George H. Zenner, Kenmore, N.`Y., assignor to The Linde Air Products Company, a corporation Application August 7, 1937, Serial No. 157,86

14 Claims.v

This invention relates to a method of and apparatus for dispensing gases stored in the liqueed state and more particularly to a method of and apparatus for supplying auxiliary oxygen for high altitude ying.

Among the -objects of the invention are to provide a method of and apparatus for dispensing gas which insure rapid pressure building; insure adequate ow being quickly attained; decrease the heat influx to the liqueiied gas -container during periods of idleness; supply heat for pressure building in proportion to the flow of' gas; and maintain constant gauge pressure independent of the rate of withdrawal and of fluctuations of atmospheric pressure caused by changes in altitude; and, further, to provide a simplied, rugged, easily disassembled gas dispensing apparatus of high unit capacity per unit of weight. These and other objects of the invention will in part be obvious and in part become apparent from a consideration of the following description in combination with the accompanying drawings, in which:

Fig. l is a simplied flow diagram showing the general principle of operation of' the invention; 1

Fig. 2 is a view, partly in section, of one form o apparatus according to the invention;

Fig. 3 is a longitudinal section of a ow control valve which may be used with any of the vi. ious forms of apparatus according to the invention;

Fig. i` is a transverse section of a modied form of apparatus according to the invention taken on line,4-4 of Fig. 5; Y

Fig. 5 is a plan view, partly in section, of th apparatus shown in Fig. 4; and

Fig. 6 is a view, partly in section, of a further modied frm of apparatus according to the invention.

For an understandingof the general method of operation of the apparatus according to the invention, reference may be had to the schematic flow diagram of Fig. 1. In this gure is shown a vacuum bottle or container I0, disposed in an outer casing or support I2, which has disposed thereon a steam chest, or other equivalent heat? ing means, I4. The container I0 is partially lled with liquefied gas through a suitable filler opening, not shown. After filling, the container I0 is sealed and a flow control valve I6 opened the desired amount.

'As soon as a slight pressure difference between the delivery side of the valve I6 and the interior of the container I0 has been created by 5?',

heat leakage into. the container I0, or by an increase in elevation of the container, as when used to Asupply oxygen for high altitude flying,'

and. superheatlng coil 20 located in the steam chest, or other heating means I4, where it is .vaporized and the vapor superheated to any desired temperature, for example, approximately atmospheric temperature. The resultant vapor then passes through a heated vapor return line 22 to` a suitable h'eat exchanging means 24 Where it gives up a portion of its heat, vaporizing some of the liqueed gas in container II) and thereby building pressure in the gas phase. above the liqueiied gas in container I0. The cooled vapor then passes through a vaporwithdrawal line 26 to a reheat coil 28, where it is again warmed, and from which it passes through a conduit .3l to the ow control valve I6.

Simultaneously the gas above the liquid in container I0 may be withdrawn through conduit 32 from which it passes through a gas heating `coil 34 and a heated gas phase withdrawal line or connection 36 to a pressure regulator 30. `Connected in the heated gas phase withdrawal line 36 are a safety valve 38 and a vent valve 40. When the gas has attained a predetermined pressure, it passes through the pressure regulator 30 and the conduit 3l to the flow control valve I6.

One form of apparatus operating in accordance with the above described general method of the invention is shown inFigs. 2 and 3, and includes a container I0 having an inner wall 42 and an outer Wall 44, the space between the same being evacuated. The inner wall 42 is provided with an inwardly extending recess 46 which is lled with absorptive silica gel, or other suitable gas absorbing material, 48, for maintaining the emciency of the vacuum in the space between Uthe walls 42 and 44. Concentric inner and outer tubular members 49 and 50 are secured respectively to the inner wall 42 and the outer wall 44 to form a neck 5I for lthe container Ii).` The container III may be. supported inv any desired manner,V such as by an outer casing or a supporting cradle. For illustrative lpurposes only,

the container Il) is shown as supported on al casing I2 by a bearing member 52 secured to the neck 5I of the container I0 and engaging a bearing member 54 mounted in a tubular exy issecured in a gas-tight manner to a closure ing screw 88.

52. Sleeve 88 terminates approximately at the center of container I8 and has no connection with gas space 18.

Extending centrally through sleeve 88 is liquid withdrawal line I8. Line I8 extends through the plug 81 to a steam chest, or other heating means I4, where it is joined to heated vapor return line 22, which passes'through the plug 81 and sleeve 88 to a heat exchanging coil 12. The heating means I4 may comprise a heating chamber having inlet and outlet openings 18 and 15, respectively, for heating iluid, or may be a fin heaterfin which material from either the liquid lor gas phase is relatively heated by a blast of air from a fan or blower, or by the.

exhaust gas discharged. by the airplane motor.

Connected to heat exchanging coil 12 is vapor withdrawal line 28 which passes through sleeve '88 and the plug 81 to the heater i 4 from which it leads through conduit 8i to a regulator block 14 shown in detail in Fig. 3. Also extending through sleeve 88 and plug 81 is the gas phase withdrawal conduit 32 which at one end has a accusa? heater I4 .where it is vaporized andthe resultant vapor is superheated. TheA superheated vapor is returned through heated vapor return line 22 to the coil 12 and passing therethrough warms and vaporizes a portion of the liquid surrounding said coil. From the opposite end of coil 12, the cooled vapor passes through the 'vapor withdrawal line 28 to the heater I4, where it is re- -heated, and from there passes through line 8l to the regulator block 14. .In owing through the regulator' block 14, the superheated vapor passes through the restricted oriii'ce 87 into the bent portion 88 terminating at an opening in sleeve 88 and secured gas-tightly in said opening.

The conduit 32 thus communicates with the space 18 above the llqueiled gas in the container I8, and at its other end is connected to a goose neck or return bend 85 communicating with the gas heating coil 34 which is connected to the regulator block 14 through connection 38.

The regulator bleek u, shown in Fig. s, has

an inlet passage 18, an inlet passage 88, of considerably smaller diameter than the inlet passage 18, and an outlet passage 82 therein. Disposed ln the passage 82 is a flow regulator valve 84 connected to an indicating handle 88, which is used to predetermine the rate of gas dispensation. Connected to passage 18 are safety valve 38 and vent valve 48. Connection 88 and line 8| are connected, respectively, to passages 18 and 88 in block 14. The passage 88 may be providedv with a restricted oriilce 81 for a purpose described hereinafter.

Rasage 18 and passage 88 terminate respectively in passages 88 and 88 which lead to one side oi' a diaphragm 88 forming part of a back pressure valve 82, which valve also comprises a cavity 84 open to theimmediate atmosphere and a spring 88 engaging at one end a spring seat secured to diaphragm 88 and lat its opposite end a spring seat engaged by a pressure adjust.

sponsive tothe diierencel between pressure ln The diaphragm 88 is thus rethe container and the immediate atmospheric pressure and, as willbe apparent from the Iolf lowing description `of' the operation lof the means 14, acts -as a' single means operating to en'ect discharge of gas from the gas space 18 when the pressure difference exceeds a predetermined gas from the gas space. v

The operation of the above described embodiment of theinvehtion vfollows .thegeneral principles demonstrated in connection with the ilow value .and to insure preferential withdrawal of s heet shown in Fig. l. Operating handlev 88 is nrst set to open valve 84 the desired amount to passages and 88 and, under certain conditions,v will iiow through the passage 82 and past the valve 84 to the consuming device or atmosphere.

The heat given up by the superheated vapor as it passes through the coil 12 vaporizes some of the liquid in the container I8, thereby causing an increase in the pressure of the gas phase accumulated in the space 18 above the liquid level in the said container. has reached a certain predetermined value, material from thegas phase will pass through the conduit 32, through the heater I4 and through connection 38 into the passage 18 in the regulator block 14. The vent 'valve 48 may be used to discharge gas from passage 18 during idlev determined by adjustment of the screw 88, the

diaphragm 88 will lift, and the gas material will passv from the passage 18 into the passage 88 and thence through the passage 82 past the valve 84 to the consuming device or atmosphere. The

discharge from the regulator block 18 is taken preferentially from the gas s'pace 16 in container I8 when the pressure exceeds the value for which valve 82 is set. For this purpose passage 18,.

withdrawalv line 32 and connection 38 are made of much larger diameter than the passage 88, line 8|, withdrawal line 28, return line 22 and liquid withdrawal line I8. If desired or necessary, the passage 88 may further be provided with the aforementioned restricted orice 81;

However, in practice this orice is not usually,

necessary since the restriction of the long tortuous withdrawal system, I8, 22, 12, and 88, for material from the liquid phase is in itself suiilcient to insure preferential withdrawal of material from gas space 18 through the withdrawal system 82, 35, 8 8, and 18.

With the above described arrangement, when diaphragm 88 is lifted the respective pressures in the passage 88 and the space 18 will be substantlally equal and balanced. Thus, there will be no pressure Vdierence available to' cause material from the liquid phase in the container I8 to ow to the regulator block 1 4. However, with the ldiaphragm 88 lifted, gas will ow from the space 18 to the regulator bloclr.` Hence, preieren tial withdrawal of gas from space 16 is assuredv whenthe diaphragm 88 is lifted. The ilow of gas from the space 18 reduces the pressure in this. space, thus tending to permit permit the proper flow of gas from the appa'- ratus. When a. slightrdiiference of pressure and the consuming device,

"fexistsrbetweenthe.interior of the container I8 v liquid oxygen passes the diaphragm 88 to lift. By proper adjustment through the liquid witndrawalline is to the "for the compression 0i 'spring 96 by.

the diaphragm 88 to be forced by the spring 488 to a closed position. On' the other hand, with-- drawal of material lfrom lthe' liquid phase tends to increase the. pressure in space 18 thus causing the screw 88,`

When thispressure the withdrawals from each phase will be balanced so that the pressure in space 16 remains at a desired x'ed value as determined by the setting of the screw 98. This causes constant gauge pressure to be maintained within the container. The term constant gauge pressure means that a xed differential pressure is maintained from inside the container to the atmosphere, regardless of variations in atmospheric pressure as with altitude.' Thus, at 28,000 feet altitude the barometric pressure is only 24'( mm. of mercury as compared with 760 mm. of mercury at sea level. This reduced atmospheric pressure affects the back pressure regulator 92, safety valve 38 and a pressure gauge, not shown, in the same manner, so that the diii'erential pressure between the 'container and atmosphere is measured and maintained. This is called gauge" pressure.

The maintenance of constant gauge pressure Within the container I produces a rate of ow through withdrawal valve 84 which remains nearly constant regardless of changes in altitude. Furthermore, with va constant gauge pressure maintained in the space 16,'a much simpler flow control may be-used than with a iiuctuating pressure.

Withl the sleeve 66 terminating at approximately the center of the container i0, the container may be placed in inverted position when it is 50 percent or less full without the pressure building up excessively. This may be of considerable advantage in aircraft installations.

Another important advantage of the above described apparatus is that it provides for rapid pressure building so that adequate now can be quickly attained vwithout the liqueiied gascontainer being susceptible to a correspondingly high heat leak during periods of idleness. The heat supplied for pressure building is proportional to the now determined by the flow control valve 84. The arrangement for maintaining constant gauge pressure in the apparatus is relatively simple and insures that such constant gauge pressure is maintained at all times regardless of external atmospheric pressure on the container.

Due to its gas-tight connection with the closure plug 61, the sleeve 66 is in communication lwith the interior of the container |0 only at its lower end which is immersed in the liquid in the said container. There is pogconnection between the gas space 16 of the container l0 and the interior of the sleeve 66. Thus, the sleeve 66, being closed at its upper end, acts as a gas collecting bell whereby the air or other gas remains in the sleeve 66 when it is inserted into the container l0 and prevents the liquid in the container I0 from rising more than a slight distance in the interior of the sleeve 66. The liquid in the container i0 is therefore only in contact with a limited portion of the various conduits leading to the exterior of the apparatus. Thus thev heat loss into the container 0 is materially reduced during idle periods because of this limited area ot contact between the liquid and any heat conducting member whch may lead to the exterior of the apparatus.

Furthermore, all tubes passing from the cap 61 to the liquid in thel container I0 are made of metals having the lowest possible thermal conductivity in order to keep normal evaporation at a minimum. Suitable metals which may be used for these tubes are nickel silver Everdur (3% silicon, 1% manganese, 96% copper) or stainless steel (18% chromium, 8% nickel, balance iron).

The above metals are given by way of example as,-

obviously, other metals of low thermal conductivity may be used.

As will be noted from Fig. 2, the pressure generating apparatus, that is, the various conduits and the heating coils 12, are all disposed within the confines .of the sleeve 66. 'Ihis permits the sleeve 66 and the pressure generating apparatus to be removed from the container as a unit by first loosening the collar 66 and then withdrawing the sleeve 66 and the pressure generating apparatus. 'I'hus one pressure generating apparatus second because there are no external connections on the reserve containers which would afford an opportunity for heatleakage thereinto while they remain in the idle state.

A modified form of apparatus embodying the invention is shown in Figs. 4 and 5. In this form of the invention an outer supporting casing |00 is provided which supports a vacuum bottle bottle |02 constructed similarly to that shown in Fig. 2 of the drawings. The outer casing is provided with a vertical tubular extension |04, tio the upper end of which is secured a collar |06 having a threaded aperture |08 therein. In the threaded aperture |06 -is threadedly secured a tubular member ||0 which forms a part of the vacuum bottle |02. Member ||0 extends completely through collar |06 and has threadedly securedv to its upper end a second tubular member M2 having a circumferential rib ||4 thereon; to which rib is secured, by bolts or other suitable means, a flat ring I6 which supports 'an annular heating chest H6. A suitable heat insulating washer H8 is placed between ringl 6 and heating chest ||6 to insure a minimum of heat conduction from the heating chest to the neck H0. Heating chest ||6 is provided with heating fluid inlet |20 and heating fluid outlet |22, and vdisposed therein are three separate heating coils |24, |26, and |28 forpurposes to be later described. Secured to the member ||2 is 'a threaded tubular member |80 which is provided at its upper portionwith a semi-circumferential rib |32 to which is` secured the inner edge of a protecting cover |34 which, at its outer edge, is secured to the iiat ring ||6. Suitable packing means are provided at each end of tubular member |30. Closing the end of tubular member |30 is a plug |36 having an aperture |38 therein in which is threadedly secured a pressure gauge |40. Supported upon the iiat ring ||6 is a flow regulating device |42 including a back pressure regulating valve |44 of the same type as the valve 92 shown in Fig. 3.

'I'he internal arrangement of vacuum bottle |82 is generally similar to thatbf the vacuum an opening in the tubular member |30 and al second opening in the ring ||6 to one end of the coil |24 disposed in the heating chest ||8. A

heated vapor return line |60 is connected to the other end of the coil |24v and extends through the ring ||6 and the tubular member |30 to the interior of the vacuum bottle |02, where it is connected to one end of a heat exchanging coil which may be similar to the heating coil l2 of Fig. 2, or may resemble the heat exchanging device 24 of Fig. 1. To the opposite end of this coil is connected a vapor withdrawal line |62 which extends through the tubular member v|30 and the ring ||6 to one end of the second coil |26 in the heating chest H8. From the opposite end oi' the heating coil |26, a conduit |64 ex' tends to the iiow regulating device |42. Gas is withdrawn from the interior space |46 oi the neck oi' the vacuum bottle |02 through an opening'l56 (see Fig. 5) to'a conduit |68 which extends to one end of the third coil |28 disposed in the heating chest IIB. From the other end of coil |28 a conduit |60 extends to the flow .regulating device- |42.

chest ||8 and out through the outlet |22. When a diil'erence of pressure has been created between the interior of the vacuum bottle 02 and the consuming apparatus, due to the reduction of atmospheric pressure or heat leakage into the bottle |02, liqueed gas is withdrawn through the liquid withdrawal line |48, is passed through the heating coil |24, where it is vaporized and the resultant vapor superheated. which latter is then returned through the heated -vapor return line |50 to the heat exchanging means in the vacuum bottle |02 wherein vit gives up some of its heat to the surrounding liquid. It then passes through the vapor withdrawal line |62 to the second heating coil |26 where it is again heated and from which ,it passes through the conduit |54 to the flow regulating. device |42.' When suiiicient pressure has been built up above the liquefied gas in the vacuum bottle |02, gas

is withdrawn through the conduit |58 to the heating coil |28 and thence to the conduit |60 from which it is delivered to the ow regulating Adevice |42. The operation of the iiow regulating device |42 is similar to thatofv the regulator block 'I4 described in connection with' Fig. 3.

As the heating means ||8 is mounted on and closely surrounds the upper portion of the support for the liquid container, a very compact arrangement is provided which permits the whole apparatus as a unit to be moved vfrom place to place with great facility and to require onlv a limited amount of space. It should be noted that the mounting of the heating apparatus utilizes available space around the neck of thecontainer without increasing the overall horizontal dimensions of the container. The apparatus described above can likewise be very quickly disassembled for repair and replacement.

Furthermore. by loosening the tubular member ||2 the4 heatingmeans and the pressure generl ating means may be removed as a unit from the liquid container, thereby providing the same advantages vas the modication described in Fig 2,

namely, the use of a -single pressure generating l means for a Vplurality, of liquid containers and the avoidance of unnecessary heat loss when the containers arelstored in the idle condition.

Fig. 6 represents a modiiied i'orm of the apparatus shown in Fig. 2, in which only a relatively small portion of the liquid in the container is heated and the main body of liquid is not disturbed, thereby allowing non-equilibrium pressure building andproviding for low heat leakage losses during periods of idleness. In this modification a container I0' is provided with a sleeve 66' similar to the sleeve 66 of Fig. 2 but extending into the container to a point adjacent the lower end of the heat exchanging coil 12'. A liquid withdrawal line |8' is disposed within the sleeve 66' and also disposed therewithin are a heated vapor return line 22 and a vapor withdrawal line 26'; respectively connected to opposite ends of the heat exchanging coil 12. A gas phase withdrawal conduit 32 extends into the sleeve 66' and terminates a short distance below the top tainer |0'. A-vent tube |80 extends from a point spaced above the heating coil 12' to an opening |82 in the sleeve 66 located above the levell of the liquid in the container l0'.

The operation of this modied apparatus v'is generally similar to the operation of the apparatus shown in Fig. 2. 'I'he sleeve 68' encloses a small vertically extending columnor core of liquid within its lower end, and this liquid may rise within the sleeve 66' until it contacts with the lower end of the vent tube |80. This vent tube is provided in order to assure that liquid will rise within the sleeve 66 to a certain extent in spite of the fact that the sleeve 66' acts as a gas bell as explained'in connection with Fig. 2. 'I'he liquid is permitted to rise` in the sleeve 66' to a point above the heating coil 12'. It then seals the end of the vent tube and'is thereby prevented from rising further within the sleeve. Liquid is withdrawn through the liquid withdrawal line l0', heated and vaporized, and the vapor is superheated and then returned through the heated vapor return line 22 to the coil 12' where it gives upl some of its heat to the liquid surrounding the coil. 'Ihe vapor, now somewhat'.V

cooled, is then withdrawn through the vapor withdrawal line 26 and reheated in the same manner as previously explained. The heat given up in the coil 12' heats and vaporizes that por- The gas produced by vaporization in sleeve 66" forces the liquid level in the sleeve to a point 1tion of the liquid disposed within the lower end I below the end oi' vent tube |80 and the gas flows through this tube into the space above theliquid in container I0' from which this gas is then discharged through the gas phase withdrawal conduit 32' and to a tlow regulator similar to those previously described.

If desired, the sleeve 66might be supported at its lower en'd on the heating coil 12' and be terminated a short distance abovelthe level oi' the liquid in the container l0'. The vent tube |80l can then be eliminated while the advantage of non-equilibrium pressure building can still be obtained. In this instance, however, the liquid phase will rise in the sleeve 66 to the level of the main body of liquid phase. 'I'he same effect can be obtained by disposing a second vent opening in the sleeve 66' above the level of the liquid in the container 4|0, or by employing, in the ernbodiment shown in Fig.y 4, a sleeve supported at its lower end on the heating coil and terminating vbuilding is produced while avoiding turbulence in the main body of liquid outside the sleeve 66. Only the top layer of liquid outside this sleeve will be heated, as by condensation of gas on the surface. The returning heated vapor passing through the heating coil 'I2' heats only that portion of the liquid which is contained within the sleeve 66', thereby avoiding heating of the main body of the liquid. Due to the pre/sence of gas phase in the sleeve 66' above the level of the liquid therein, a heat insulating eect is obtained which prevents transmission of heat to the main body of liquid. At the same time, because the main body of liquid is not heated during utilization of theapparatus, there'is less subsequent loss of gas phase by evaporation. Furthermore, because of the insulating layer of gas along the inside oi the sleeve 66', there is little transmission of heat from the apparatus which extends to Athe outside of the uquid in thev container In' dur-l ing idle periods. As in the apparatus shown in Fig. 2, the entire pressure-building arrangement can be withdrawn through the neck of the vacuum bottle, and accordingly only one pressurebuilding apparatus is needed for a number of liquid containers, and during periods of idleness there are no external connections to the liquid containers allowing heat to enter thereinto and cause a loss of vapor therefrom. Obviously, any one of the modifications ofthe apparatus shown in Fig. 6 can be substituted for the pressure generating means shown in Fig. 2.

If the lower end of the sleeve 66' vis -supported on the heating coil 12 and the sleeve is ter.- minated just above the level of the liquid in thecontainer, it will no longer act as a gas collecting bell but will still permit of heating only the small core of liquid contained therein and not heating the main body of liquid inthe container This is ano true of this construction when a. vent is added in the sleeve 66' above the liquid levelin the main container. Both of these latter expedients will likewise result in low heat leak into the container l and low heat loss during operation as described above.

Although several embodiments of the invention are disclosed in detail, it will be evident that numerous changes may be made in such details without departing from 'the principles -oi the invention. A y i What is claimed is: v-

1. A liquefied gas container; a heating coil disposed in said container; a tubular extensionA connected to said container; a tubular member disposed concentrically of said tubularA extension and extending into said container; said heating coil being aligned with said tubular member; a

tubular member; a means for maintaining the level of liquid within said tubular member above said heating coil.

2. A liqueiied gas container; a heating coil disposed in said container; a tubular extension connected to said container; a tubular member disposed concentrically of said tubular extension and extending into said container; said heating coil being yaligned with said tubular member; a

means formaintaining the level of liquid within said tubular member at a desired point below the level of liquid in the container.

3. Gas dispensing apparatus including a con- I tainer for liqueiied gas having a tubular extension thereon; asupport for said container surrounding the same and having a tubular extension thereon concentric with' and disposed externally o1' said iirst mentioned tubular extension; a heating chamber surrounding said second-named tubular extension and supported thereby; a plurality of heating coils disposed in said heating chambers; conduits connecting certain of said coils with said container; and other conduits connecting certain'of said coils with a ilow regulating device.

4. Gas dispensing apparatus including a container for liqueiied gas and a tubular extension attached thereto; a heating chamber concentric with and supported by said tubular extension; a

flow regulating device also supported by said tubular extension; a plurality ofheating coils disposed insaid heating chamber; a liquid withdrawal' conduit and a heated vapor return conduit disposed in said container and connected to opposite ends of one of said coils; a cooled vapor withdrawal conduit disposed in' said container and connected to one end of another of said coils; a gas phase withdrawal conduit in communication with said tubular extension and connected to a third of said heating coils; and conduits leading respectively from each of Said second and third heating coils to said now regulating device. v

5. Gas dispensing apparatus including a container for liquefied gas, a heating means disposed adjacent said container; a liquid withdrawal conduit, a heated vapor return conduit, a cooled lvapor withdrawal conduit, and a gas phase withdrawal conduit, extending between said container gas phase withdrawal conduit disposed in'said j tubular member and communicating with the space above the liquid in said container; and

in said container, the opposite ends of which are connected respectivelyto said heated vapor return conduit and said cooled vapor withdrawal conduit; and a sleevesurrounding said liquid withdrawal conduit, said heated vapor return conduit, and said cooled vapor withdrawal conduit, said sleeve extending at least half-way into said container and terminating at its lower end above said heating coil.

6. In gas dispensing apparatus, a container for liquefied gas; a tubular extension connected thereto; a tubular member disposed concentrically of said tubular extension and extending into said container at least half-way; liquid withdrawal, heated vapor return, cooled vapor withdrawal, and gas phase withdrawal conduits disposed inside oi said tubular member; a heating coil disposed in said container below the end of said tubular member and having its end portions connected respectively to said heated vapor return and said cooled vapor withdrawal conduits;

gas phase withdrawal conduit disposed in said Said liquid Withdrawal and gas Phase Withdrawal conduits extending from said tubular extension to heatingmeans, and said gas phase withdrawal duced; a unitary ow regulating means; a coni duit for conducting said superheated vapor to said ilow regulating means; means for withdrawing gas from the gas space above the liquid in 6 said container and conducting said gas to said flow regulating means; and means incorporated in said ow regulating means for effecting the withdrawal of v apor only when the gauge pressure in said Vcontainer is below a predetermined value, for permitting withdrawal of gas from said gas space when said pressure exceeds said predetermined value, and for insuring preferential iiow of gas from said gas space when said pressure exceeds said predetermined value.

8. In gas dispensing apparatus comprising a container for liquefied gas having a gas space therein above the liquid; a heating coil in the vllquidspace of said container; vaporizing and superheating means; gas heating means; a liquid withdrawal conduit connecting the liquid space of said container to said vaporizing and superheating means; a superheated vapor conduit conand enclosing a substantially vertical column thereof means for heating said. column of lique--vned gas so as to gasify a portion thereof; and a single means -for conducting the resultant gas from within said tubular member to the space above the level of the liqueed gas within said container, andfor limiting the rise of the liquefled gas within .said tubular memberto a' level below that of the liquefied gasl within said container.

11. The method of dispensing gas material from a container of liquefied, gas which comprises heating a definitely limited volume of said liquefied gas located within the main body thereof; confining the gas so produced to ilow solely through said denitely limited volume to the space above the main body of said liqueiied gas;

necting said vaporizing and superheating means to one end of said heating coil; means connecting the gas space of said container to said gas heating means; a flow regulating device; a cooled vapor conduit conducting vapor from the opposite end of said heating coil to said device; a con- `duit connecting said gas heating means to said device; a single means incorporated in said device and responsive to the difference between the pressure in said container and the immediate atmospheric pressure, said single means operating to effect discharge of gas from said gas space only when said pressure difference exceeds a predetermined value; and an orifice in saidA device restrictingthe ow of said vapor through said device for insuring the preferential discharge of gas from said gas space when said pressure difference exceeds said predetermined value 9. Gas dispensing apparatus'including a con tainer for liquefied gas and having a space above -said liqueed .Sas for material in the gas phase; means for withdrawing from said container and heating liqueed gas; means for transferring heat from such heated gas tothe liquei'led gas within said container; and a tubular member surrounding such heat transferring means, said tubular member beinig supported by such heat transferring means in a vertical position and being in direct communication with the gas phase in the space above the. liquefied gas ln said container.

10. Gas dispensing apparatus including a container for liquefied gas having a space therein above the levelv of the liquefied gas for material and withdrawing said gas from said space.

12. The Amethod of dispensing gas material vfrom a container of liquefied gas which comprises substantially fully enclosing a vertically extending column of said liquefied gas lwithin the main body thereof; withdrawing liquid from the main body of liquid; vaporizing said withdrawn liquid and superheating the resultant vapor; indirectly passing such superheated vapor only through said column of liqueed gas; reheating said va' por; and withdrawing gas from the space'directly above said column of liquefied gas.

13. The method of dispensing gas from a container of liquefied. gas which comprises withdrawing liquid from said container, vaporizing said withdrawn liquid and superhating the resultant vapor, transferring heat from such superheated vapor to a definitely. limited volume of the main body ofthe liquid in said container; reheating said vapor; and the space directly above said definitely limited volume of liquid.

-l4. The method of dispensing gas from a container of liqueed gas which"y comprises substantially fully enclosing a vertically extending col-1 umn of the main body of liquid in said container 'while providing for liquid communication be.

said space. v

' GEORGE H. ZENNER.

withdrawing gas from 

